<!DOCTYPE html>
<html lang="zh_CN">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>

</body>
<script type="text/javascript">
    var arr = [1, 2, 3, 4];
    console.log(arr.join('+')); // join 有拼接的意思，把数组元素按照参数的分隔符进行拼接
    console.log(arr.join('&&'));



</script>

</html>
